Stabilised ferroportin activity affects pulmonary vascular cells responses: implications for pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterised by vascular remodelling of pulmonary arterioles. Disrupted iron homeostasis and elevated hepcidin are implicated in PAH, although exact mechanisms remain unknown. Hepcidin targets ferroportin, the only known iron exporter to cause its internalisation. Earlier we established the expression of ferroportin in human pulmonary artery smooth muscle cells (hPASMCs) and also demonstrated its enhanced proliferation and migration when exposed to hepcidin conditioned media (HCM) from pulmonary artery endothelial cells (hPAECs). In this study, we further explored the dose dependent effect of hepcidin in the CM, its role in ferroportin expression and the ability of LY2928057-mAb against ferroportin in reversing responses elicited by HCM. hPAECs were challenged with hepcidin (0.1-1ug/mL). Proliferation and migration were analysed using xCELLigence RTCA by measuring the changes in cell index. Ferroportin expression was analysed by immunocytochemistry; GDF-15 and IREB2 were quantified by ELISA. In the absence of hPAECs, HCM had little or no effect on either proliferation or migration of hPASMCs. Confocal imaging revealed decreased ferroportin expression in hPASMC treated with HCM from hPAECs compared to HCM without hPAECs. LY2928057, inhibited proliferation induced by HCM and also decreased IREB2 levels in hPASMCs. LY2928057 also increased GDF-15 expression in hepcidin-treated hPAECs. Together these data suggest a vital role for the hepcidin-ferroportin axes in controlling proliferation, migration and release of mediators by pulmonary vascular cells, relevant to PAH and that LY2928057 could potentially reverse some these effects